When I ran the script manually I was surprised to find it ran rather quickly, so I opened a command window and ran one of the lines manually
I got the error message

mysqldump: unknown option ‘–no-beep’

I tried again – this time with just the mysqldump and got the same error

After a bit of Googling where I found this article from StackOverflow – What’s wrong with mysqldump? – which explained that I’d put the “no-beep” in the my.cnf configuration file under the [client] section, which applies to both mysql and mysqldump clients, and that I should have put it in the [mysql] section of the config file, so it applies only to the mysql client.

So off I went to have a look at the my.cnf file and yes – no-beep was immediately below the [client] line. Moving it to below [mysql] fixed this (Phew – I can backup my test databases again). The however is – however, I never put it there, it was there in the install files.

Oh well – it looks like Microsoft aren’t the only people to release buggy software 🙂